Power storage module manufacturing method

Abstract

To provide a power storage module manufacturing method capable of inspecting the airtightness of power storage cells.SOLUTION: A power storage module manufacturing method includes a step S10 of preparing a module 1A for inspection, and an inspection step S20 of inspecting the module 1A for airtightness inspection. The step S20 includes a step S201 of placing the module 1A for inspection in a vacuum chamber CH, a step S202 of reducing the pressure in the vacuum chamber CH, and steps S203 and S204 of determining the airtightness of each of power storage cells C after or during the step S202 on the basis of the deformation state of each of frame sealing portions 41 of a film 40 of the module 1A for inspection.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing an electricity storage module. [Background technology]

[0002] Patent Document 1 describes a method for inspecting the airtightness of a battery. In a battery to be inspected by this inspection method, a cell, which is a power generating element, has a multi-layer structure in which a separator is sandwiched between a positive electrode layer and a negative electrode layer, and is sealed in an exterior container. An exterior container that houses such a cell is generally made of a flexible sheet-like exterior material in which a resin layer is provided on both sides of a metal foil such as aluminum. The exterior container is then placed in a vacuum atmosphere, or the opening is sealed while the interior of the container is evacuated.

[0003] In the inspection method of Patent Document 1, first, the above-mentioned battery is set in a battery holder in a vacuum chamber. Next, a vacuum pump is operated to evacuate the vacuum chamber. When the battery is placed in the vacuum chamber and the pressure is gradually reduced, the outer container expands outward, and this change is detected by a micrometer. Then, the pressure in the vacuum chamber is measured when the outer container starts to expand. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-327097 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the inspection method of Patent Document 1, in a battery in which multiple stacked electrodes are housed in a single exterior container, with the interior of the exterior container being one cell space, expansion of the exterior container is detected to determine whether the airtightness of the battery is maintained. In contrast, in a battery in which the volume of the internal space of each cell is much smaller than the volume of the cell space in Patent Document 1, such as a bipolar battery constructed by stacking multiple airtightly sealed cells, it is difficult to inspect the airtightness of each cell (internal space) based on deformation of the battery cell as in the inspection method of Patent Document 1.

[0006] An object of the present disclosure is to provide a method for manufacturing an energy storage module that is capable of inspecting the airtightness of energy storage cells. [Means for solving the problem]

[0007] The method for manufacturing an energy storage module according to the present disclosure includes a preparation step of preparing an inspected module having a stack in which a plurality of energy storage cells, each having a reduced pressure internal space, are stacked along a first direction, a sealing body provided on the stack so as to seal the internal space of the energy storage cell, a sealing body provided on the stack so as to seal the internal space, a frame member provided on an outer surface of the sealing body along the first direction, and a film provided on a surface opposite to the outer surface of the frame member, and an inspection step of performing an airtight inspection of the inspected module after the preparation step, wherein the sealing body has a plurality of communication holes formed therein that communicate with the internal spaces of the plurality of energy storage cells and open to the outer surface, The component includes a plurality of frame portions surrounding each of the openings of the multiple communication holes when viewed from a second direction intersecting the outer surface, and the length in the first direction of the space surrounded by the frame portions is greater than the thickness in the first direction of the storage cell, and the film includes a plurality of frame sealing portions for sealing the spaces surrounded by each of the multiple frame portions, and the inspection process includes a first step of placing the module to be inspected in a vacuum chamber, a second step of reducing the pressure in the vacuum chamber after the first step, and a third step of determining the airtightness of each of the multiple storage cells based on the deformation state of each of the multiple frame sealing portions of the film after or during the second step.

[0008] In this manufacturing method, after preparing a module to be inspected, an inspection process is performed to inspect the module to be inspected for airtightness. The module to be inspected includes a reduced-pressure internal space and includes a plurality of stacked storage cells. The internal space is in communication with a space surrounded by a frame portion of a frame member provided on an outer surface of the sealing body through a communication hole of the sealing body. The internal space is sealed by providing a film including a plurality of frame sealing portions for sealing the spaces surrounded by the plurality of frame portions on the frame member. In the inspection process, the module to be inspected is placed in a vacuum chamber, and then the vacuum chamber is depressurized. Then, an airtightness judgment is performed for each of the plurality of storage cells based on the deformation state of each of the plurality of frame sealing portions of the film. This makes it possible to inspect the airtightness of each storage cell. In particular, the length of the frame portion of the frame member in the stacking direction (first direction) of the storage cells is greater than the thickness of the storage cells in the same direction. Therefore, the frame sealing portion that seals the frame portion of the film also has a certain length greater than the thickness of the storage cells, and therefore the deformation is easily detected. Therefore, even if the energy storage cell is thin, deformation of the frame sealing portion can be easily detected, and the airtightness of the energy storage cell can be reliably inspected.

[0009] In the energy storage module manufacturing method according to the present disclosure, before the second step, each of the multiple frame sealing parts of the film may be convex toward the inside, and in the third step, when the pressure is reduced to the threshold value in the second step or while the pressure is being reduced to the threshold value, if one of the multiple frame sealing parts is detected that has deformed to be convex toward the outside, it may be determined that there is an air leak in the energy storage cell corresponding to that frame sealing part. In this case, it is possible to reliably determine whether there is an air leak in the energy storage cell.

[0010] In the energy storage module manufacturing method according to the present disclosure, each of the multiple frame sealing parts may be formed with a flexible part that is relatively more flexible than other parts. In this case, the frame sealing part is more likely to deform at the flexible part. Therefore, it is possible to more easily detect the deformation of the frame sealing part and more reliably inspect the airtightness of the energy storage cell. Note that the energy storage cell corresponding to the frame sealing part is a single energy storage cell that includes an internal space that communicates with a space surrounded by a frame part sealed by a single frame sealing part via a communication hole in the sealing body.

[0011] In the energy storage module manufacturing method according to the present disclosure, the film may be made of resin. In this case, since the frame sealing portion is more easily deformed than when the frame sealing portion is made of, for example, a laminate film including a metal layer, it is possible to more easily detect deformation of the frame sealing portion and more reliably inspect the airtightness of the energy storage cell.

[0012] The method for manufacturing an energy storage module according to the present disclosure may further include an exterior packaging step of sealing the inspected module with an exterior packaging film after the inspection step. In this case, it is possible to obtain an energy storage module with improved airtightness. Effect of the Invention

[0013] According to the present disclosure, it is possible to provide a method for manufacturing an energy storage module that is capable of inspecting the airtightness of energy storage cells. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an electricity storage module according to this embodiment. [Diagram 2] FIG. 2 is a schematic cross-sectional view of the electricity storage module shown in FIG. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing an enlarged portion of FIG. [Figure 4] FIG. 4 is a schematic partial side view of the frame member as seen from the outer surface side where the openings of the communication holes in the sealing body are provided. [Diagram 5]FIG. 5 is a schematic side view showing the relationship between the opening of the communication hole and the frame member. [Figure 6] FIG. 6 is a flowchart showing main steps of the energy storage module manufacturing method according to this embodiment. [Figure 7] FIG. 7 is a schematic side view showing one step shown in FIG. [Figure 8] FIG. 8 is a flow chart showing each step of the airtightness inspection shown in FIG. [Figure 9] FIG. 9 is a schematic diagram showing one step of the flowchart shown in FIG. [Figure 10] FIG. 10 is a schematic diagram showing one step of the flowchart shown in FIG. [Figure 11] FIG. 11 is a schematic cross-sectional view showing a film according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an energy storage module and an energy storage module manufacturing method according to an embodiment will be described with reference to the drawings. In the description of each drawing, the same or corresponding elements are given the same reference numerals, and duplicated descriptions may be omitted. In addition, each drawing may show an orthogonal coordinate system that defines a first direction D1, a second direction D2 perpendicular to the first direction D1, and a third direction D3 perpendicular to the first direction D1 and the second direction D2.

[0016] Fig. 1 is a schematic cross-sectional view showing an energy storage module according to this embodiment. The packaged module 100 shown in Fig. 1 is constructed by sealing an energy storage module 1 with an exterior film 90. The exterior film 90 includes a first film portion 91 provided on one side of the energy storage module 1 in the first direction D1, and a second film portion 92 provided on the other side of the energy storage module 1 in the first direction D1.

[0017] The exterior film 90 is formed of, for example, a laminate film configured by sequentially laminating a first resin layer 93, a metal layer 94, and a second resin layer 95. The metal layer 94 is, for example, aluminum foil. One end of the first film portion 91 and one end of the second film portion 92 are hermetically joined to each other on a side surface of the energy storage module 1 along the first direction D1 to form a sealing portion 90p. In the sealing portion 90p, the first resin layer 93 of the first film portion 91 and the first resin layer 93 of the second film portion 92 are joined. The first film portion 91 and the second film portion 92 are joined in a state in which insulation is ensured.

[0018] The first film portion 91 has an opening on one end surface of the energy storage module 1 in the first direction D1 (a second surface 15b of a current collector 15 of a positive terminal electrode 13 described later). A conductive member 97 is interposed between the first film portion 91 and the one end surface of the energy storage module 1 so as to cover the opening. The conductive member 97 is electrically connected to the current collector 15 of the positive terminal electrode 13. A region of the conductive member 97 exposed from the first film portion 91 serves as a terminal surface of the packaged module 100. The conductive member 97 is made of a metal foil having good electrical conductivity, such as aluminum foil or stainless steel foil. The first film portion 91 and the conductive member 97 are hermetically joined via an insulating resin material, and their mutual insulation is ensured.

[0019] The second film portion 92 has an opening on the other end surface of the energy storage module 1 in the first direction D1 (a first surface 15a of a current collector 15 of a negative terminal electrode 12 described later). A conductive member 98 is interposed between the second film portion 92 and the other end surface of the energy storage module 1 so as to cover the opening. The conductive member 98 is electrically connected to the current collector 15 of the negative terminal electrode 12. An area of ​​the conductive member 98 exposed from the second film portion 92 serves as a terminal surface of the packaged module 100. The conductive member 98 is made of a metal foil having good electrical conductivity, such as aluminum foil or stainless steel foil. The second film portion 92 and the conductive member 98 are hermetically joined via an insulating resin material, ensuring their mutual insulation.

[0020] Fig. 2 is a schematic cross-sectional view of the power storage module shown in Fig. 1. Fig. 3 is a schematic cross-sectional view showing an enlarged portion of Fig. 2. The power storage module 1 shown in Figs. 2 and 3 is used in batteries for various vehicles such as forklifts, hybrid cars, and electric cars. The power storage module 1 is a secondary battery such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery. The power storage module 1 may be an electric double layer capacitor or an all-solid-state battery. Here, a case where the power storage module 1 is a lithium-ion secondary battery is illustrated as an example.

[0021] The energy storage module 1 includes an electrode laminate (laminate) 10, a sealing body 20, a frame member 30, and a film 40. The electrode laminate 10 includes a plurality of electrodes laminated along a first direction D1. The plurality of electrodes include a plurality of bipolar electrodes 11, a negative terminal electrode 12, and a positive terminal electrode 13. Separators 14 are interposed between adjacent electrodes.

[0022] The bipolar electrode 11 has a current collector 15, a positive electrode active material layer 16, and a negative electrode active material layer 17. The current collector 15 has, for example, a rectangular sheet shape. The current collector 15 includes a first surface 15a and a second surface 15b. As an example, the first surface 15a is a surface that intersects with the first direction D1, and the second surface 15b is a surface that intersects with the first direction D1 and is opposite to the first surface 15a. Here, the first surface 15a of the current collector 15 is a surface that faces one side of the first direction D1 (the direction from the positive electrode terminal electrode 13 to the negative electrode terminal electrode 12 in FIG. 2), and the second surface 15b of the current collector 15 is a surface that faces the other side of the first direction (the direction from the negative electrode terminal electrode 12 to the positive electrode terminal electrode 13 in FIG. 2).

[0023] The positive electrode active material layer 16 is provided on the first surface 15a of the current collector 15. The negative electrode active material layer 17 is provided on the second surface 15b of the current collector 15. The peripheral portion surrounding the positive electrode active material layer 16 on the first surface 15a of the current collector 15 and the peripheral portion surrounding the negative electrode active material layer 17 on the second surface 15b of the current collector 15 are each an unformed region (uncoated region) where no active material layer is provided. The multiple bipolar electrodes 11 are stacked such that the positive electrode active material layer 16 of one bipolar electrode 11 and the negative electrode active material layer 17 of another bipolar electrode 11 face each other via the separator 14. The positive electrode active material layer 16 and the negative electrode active material layer 17 of each bipolar electrode 11 may have grooves formed therein to improve liquid injectability and gas escape properties.

[0024] The positive electrode active material layer 16 and the negative electrode active material layer 17 are rectangular when viewed from the first direction D1. The negative electrode active material layer 17 is slightly larger than the positive electrode active material layer 16 when viewed from the first direction D1. In a plan view viewed from the first direction D1, the entire formation region of the positive electrode active material layer 16 is located within the formation region of the negative electrode active material layer 17. In other words, when viewed from the first direction D1, the outer edge 17e of the negative electrode active material layer 17 is located outside the outer edge 16e of the positive electrode active material layer 16.

[0025] The negative electrode terminal electrode 12 has a current collector 15 and a negative electrode active material layer 17 provided on the second surface 15b of the current collector 15. The negative electrode terminal electrode 12 does not have a positive electrode active material layer 16 and a negative electrode active material layer 17 on the first surface 15a of the current collector 15. In other words, the first surface 15a of the current collector 15 of the negative electrode terminal electrode 12 does not have an active material layer and constitutes the negative electrode terminal surface of the power storage module 1. The negative electrode terminal electrode 12 is laminated on the bipolar electrode 11 at one end of the electrode laminate 10 in the first direction D1. The negative electrode terminal electrode 12 is laminated on the bipolar electrode 11 via the separator 14 so that the negative electrode active material layer 17 faces the positive electrode active material layer 16 of the bipolar electrode 11.

[0026] The positive electrode terminal electrode 13 has a current collector 15 and a positive electrode active material layer 16 provided on a first surface 15a of the current collector 15. The positive electrode terminal electrode 13 does not have a positive electrode active material layer 16 or a negative electrode active material layer 17 on a second surface 15b, which is the surface opposite to the first surface 15a of the current collector 15. In other words, the second surface 15b of the current collector 15 of the positive electrode terminal electrode 13 does not have an active material layer and constitutes a positive electrode terminal surface of the electricity storage module 1. The positive electrode terminal electrode 13 is laminated on the bipolar electrode 11 at one end of the electrode laminate 10 in the first direction D1. The positive electrode terminal electrode 13 is laminated on the bipolar electrode 11 so that the positive electrode active material layer 16 faces the negative electrode active material layer 17 of the bipolar electrode 11 via the separator 14.

[0027] In this embodiment, the current collectors of the bipolar electrode 11, the negative terminal electrode 12, and the positive terminal electrode 13 are denoted by the same reference numeral 15, but the materials constituting the current collectors of the bipolar electrode 11, the negative terminal electrode 12, and the positive terminal electrode 13 may be the same as or different from each other.

[0028] The separators 14 are disposed between the bipolar electrodes 11 adjacent to each other in the first direction D1, between the negative terminal electrode 12 and the bipolar electrode 11, and between the positive terminal electrode 13 and the bipolar electrode 11. That is, the separators 14 are disposed between the positive electrode surface of the current collector 15 on which the positive electrode active material layer 16 is provided and the negative electrode surface on which the negative electrode active material layer 17 is provided. The separators 14 are members that allow charge carriers such as lithium ions to pass through, and prevent short circuits caused by contact between adjacent electrodes by isolating the positive electrode surface from the negative electrode surface.

[0029] The current collector 15 is a chemically inactive electrical conductor for continuously passing a current through the positive electrode active material layer 16 and the negative electrode active material layer 17 during discharging or charging of the lithium ion secondary battery. The material of the current collector 15 is, for example, a metal material, a conductive resin material, or a conductive inorganic material. Examples of the conductive resin material include resins in which a conductive filler is added to a conductive polymer material or a non-conductive polymer material as necessary. The current collector 15 may have a plurality of layers. In this case, each layer of the current collector 15 may contain the above-mentioned metal material and / or conductive resin material.

[0030] A coating layer may be formed on the surface of the current collector 15. The coating layer may be formed by a known method such as plating or spray coating. The current collector 15 may be, for example, in the form of a plate, foil, film, or mesh. Examples of the metal foil include aluminum foil, copper foil, nickel foil, titanium foil, and stainless steel foil. The current collector 15 may be an alloy foil of the above metals or a foil obtained by integrating a plurality of metal foils. When the current collector 15 is in the form of a foil, the thickness of the current collector 15 may be, for example, 1 μm to 200 μm. The current collector 15 may be a foil obtained by integrating an aluminum foil and a copper foil by bonding them together via a conductive adhesive, or a foil obtained by vapor-depositing a copper layer on one side of an aluminum foil.

[0031] The positive electrode active material layer 16 contains a positive electrode active material capable of absorbing and releasing charge carriers such as lithium ions. Examples of the positive electrode active material include lithium composite metal oxides having a layered rock salt structure, metal oxides having a spinel structure, polyanion compounds, and the like. The positive electrode active material may be any material that can be used in lithium ion secondary batteries. The positive electrode active material layer 16 may contain a plurality of positive electrode active materials. In this embodiment, the positive electrode active material layer 16 contains olivine-type lithium iron phosphate (LiFePO4) as a composite oxide.

[0032] The negative electrode active material layer 17 includes a negative electrode active material capable of absorbing and releasing charge carriers such as lithium ions. The negative electrode active material may be any of a simple substance, an alloy, or a compound. Examples of the negative electrode active material include Li, carbon, and metal compounds. The negative electrode active material may be an element capable of being alloyed with lithium or a compound thereof. Examples of carbon include natural graphite, artificial graphite, hard carbon (hardly graphitizable carbon), and soft carbon (easily graphitizable carbon). Examples of artificial graphite include highly oriented graphite and mesocarbon microbeads. Examples of elements capable of being alloyed with lithium include silicon and tin. In this embodiment, the negative electrode active material layer 17 includes graphite as a carbon-based material.

[0033] Each of the positive electrode active material layer 16 and the negative electrode active material layer 17 (hereinafter sometimes simply referred to as "active material layer") may further contain a conductive assistant, a binder, an electrolyte, an electrolyte supporting salt, and the like, as necessary. The conductive assistant is added to enhance electrical conductivity. Examples of the conductive assistant include acetylene black, carbon black, and graphite. The electrolyte supporting salt is added to enhance ionic conductivity.

[0034] Examples of the binder include fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluorine rubber, thermoplastic resins such as polypropylene and polyethylene, imide resins such as polyimide and polyamideimide, alkoxysilyl group-containing resins, acrylic resins such as acrylic acid or methacrylic acid, styrene-butadiene rubber, carboxymethyl cellulose, alginates such as sodium alginate and ammonium alginate, water-soluble cellulose ester crosslinked bodies, and starch-acrylic acid graft polymers. These binders may be used alone or in combination. Examples of the solvent for the binder include water and N-methyl-2-pyrrolidone.

[0035] The separator 14 may be, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains an electrolyte. Examples of materials for the separator 14 include polypropylene, polyethylene, polyolefin, polyester, and the like. The separator 14 may have a single-layer structure or a multi-layer structure. The multi-layer structure may have, for example, a ceramic layer as an adhesive layer or a heat-resistant layer. The separator 14 may be impregnated with an electrolyte. The electrolyte impregnated in the separator 14 is a liquid electrolyte (electrolytic solution) containing a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.

[0036] As the electrolyte salt of the electrolytic solution, known lithium salts such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, and LiN(CF3SO2)2 may be used. As the non-aqueous solvent, known solvents such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, and ethers may be used. Two or more of these known solvent materials may be used in combination.

[0037] The sealing body 20 is provided on the electrode stack 10 so as to surround the electrode stack 10 when viewed from the Z direction. For example, the sealing body 20 is formed on the periphery of the electrode stack 10 as a rectangular tubular member so as to surround four side surfaces of the electrode stack 10, which is a substantially rectangular parallelepiped shape. The sealing body 20 can be joined (welded) to each of the first surface 15a and the second surface 15b of the current collector 15 at the periphery 15c of each current collector 15. The sealing body 20 forms an internal space S in cooperation with the adjacent current collectors 15 while insulating the current collectors 15 adjacent to each other in the first direction D1. The sealing body 20 is for sealing each of the internal spaces S. An electrolyte is accommodated in each internal space S. The sealing body 20 can suppress the electrolyte accommodated in the internal space S from leaking out to the outside. Furthermore, the sealing body 20 can prevent air, moisture, and the like from entering the internal space S from the outside of the electrode stack 10.

[0038] The sealing body 20 includes an insulating material. Examples of the material of the sealing body 20 include various resin materials such as polypropylene, polyethylene, polystyrene, ABS resin, acid-modified polypropylene, acid-modified polyethylene, and acrylonitrile-styrene resin.

[0039] The sealing body 20 includes a plurality of resin sealants 21 and a plurality of resin spacers 22. The sealants 21 are provided on each of the plurality of electrodes. More specifically, the sealants 21 are provided on each of the peripheral portions 15c of the current collector 15. Thus, the plurality of sealants 21 are stacked along the first direction D1. The sealants 21 provided on the peripheral portions 15c of the current collector 15 are formed in a frame shape that follows the outer shape of the current collector 15 when viewed from the first direction D1. Here, since the current collector 15 is rectangular in plan view, the sealants 21 are rectangular in plan view. The sealants 21 include an inner portion that overlaps with the peripheral portion 15c of the current collector 15 when viewed from the first direction D1, and an outer portion that protrudes outward beyond the edge of the current collector 15. The seal material 21 is formed by joining together and integrating an outer portion of a first resin member joined to the first surface 15a of the current collector 15 and a second resin member joined to the second surface 15b of the current collector 15. That is, the seal material 21 covers the peripheral portion 15c of the current collector 15.

[0040] In this embodiment, the sealing materials provided on the current collector 15 of the bipolar electrode 11, the current collector 15 of the negative terminal electrode 12, and the current collector 15 of the positive terminal electrode 13 are given the same reference numeral as the sealing material 21. However, the sealing material provided on the current collector 15 of the bipolar electrode 11, the sealing material provided on the current collector 15 of the negative terminal electrode 12, and the sealing material provided on the current collector 15 of the positive terminal electrode 13 may be the same as or different from each other.

[0041] The spacer 22 is formed in a substantially frame shape so as to surround the positive electrode active material layer 16 when viewed from the first direction D1. When viewed from the first direction D1, the spacer 22 has an inner portion overlapping the current collector 15 and an outer portion extending outward beyond the edge of the current collector 15. The spacer 22 is disposed so as to be interposed between the seal materials 21 provided on the electrodes adjacent to each other in the first direction D1. As a result, the spacer 22, together with a pair of seal materials 21 adjacent to each other in the first direction D1, maintains the interval between the current collectors 15 adjacent to each other in the first direction D1. An internal space S is defined by the pair of current collectors 15 adjacent to each other in the first direction D1, the spacer 22, and the pair of seal materials 21 adjacent to the spacer 22.

[0042] The end of the separator 14 may be held by being sandwiched between the seal material 21 and the spacer 22. The end of the separator 14 may be fixed to at least one of the seal material 21 and the spacer 22 by welding.

[0043] The outer ends of the plurality of sealants 21 and the outer ends of the plurality of spacers 22 are welded together to form a welded portion 23. That is, the sealing body 20 includes the welded portion 23 formed by welding the plurality of sealants 21 and the plurality of spacers 22 together. The welded portion 23 has a frame shape (here, a rectangular frame shape) surrounding the electrode stack 10 when viewed from the first direction D1, and forms the outer periphery of the sealing body 20. Therefore, the outer side surface 23s of the welded portion 23 forms the outer side surface of the sealing body 20. That is, in this embodiment, the sealing body 20 has four outer sides 23s extending along the first direction D1. The spacers 22 may not be welded to the sealing material 21 at least in the inner portion of the sealing material 21 adjacent to the first direction D1.

[0044] Conductive members 97, 98 (see FIG. 1 ) are laminated on the second surface 15b of the current collector 15 of the negative terminal electrode 12 and on the exposed portion of the first surface 15a of the current collector 15 of the positive terminal electrode 13 that is not covered by the sealing body 20 (i.e., the portion where the seal material 21 is not provided when viewed from the first direction D1). The conductive members 97, 98 can be used to extract current from the electricity storage module 1. When a battery pack is formed by stacking a plurality of exterior-mounted modules 100 in the first direction D1 and connecting them in series, a conductive plate, a conductive adhesive, or the like is disposed between two exterior-mounted modules 100 adjacent to each other in the first direction D1 to electrically connect the plurality of exterior-mounted modules 100. That is, the conductive members 97, 98 can be used to electrically connect the plurality of electricity storage modules 1.

[0045] When viewed from the first direction D1, the inner edge 22e of the spacer 22 is located between the outer edge 17e of the negative electrode active material layer 17 and the outer edge 16e of the positive electrode active material layer 16. As a result, the spacer 22 includes a portion overlapping the negative electrode active material layer 17 when viewed from the first direction D1.

[0046] The spacers 22 may be configured not to contact the current collectors 15 of the adjacent bipolar electrodes 11. In other words, a minute gap may be provided between the spacers 22 and the first surfaces 15a of the current collectors 15 of the adjacent bipolar electrodes.

[0047] Here, the sealing body 20 has a plurality of communication holes 31 that communicate with each of the plurality of internal spaces S. One communication hole 31 is connected to one internal space S. The communication hole 31 communicates the internal space S with the outside of the electricity storage module 1. The communication hole 31 is formed as a through hole penetrating the sealing body 20 by, for example, cutting out a part of the spacer 22. One opening 31A of the communication hole 31 is provided on one outer side surface 23s of the sealing body 20, and the other opening 31B is provided on a surface of the sealing body 20 facing the internal space S. In the electricity storage module 1, one storage cell C is formed by a pair of current collectors 15 adjacent to each other along the first direction D1. The storage cell C includes the current collectors 15 of a pair of electrodes adjacent to each other in the first direction, the internal space S between the pair of current collectors 15, and a part of the sealing body 20 that seals the internal space S. Therefore, the electrode stack 10 includes a plurality of storage cells C arranged along the first direction D1. Each of the plurality of communication holes 31 communicates with an internal space S of one of the storage cells C.

[0048] The frame member 30 is provided on an outer side surface 23s of the sealing body 20 along the first direction D1. In this embodiment, the frame member 30 is provided on one of the four outer sides 23s of the sealing body 20, on which the opening 31A of the communication hole 31 is provided. A film 40 is provided on the surface of the frame member 30 opposite the outer side surface 23s to prevent electrolytes contained in the energy storage cells C, such as electrolytic solution, from leaking out of the energy storage module 1. The film 40 is, for example, a sheet member made of resin, and is joined to the frame member 30 to seal the internal space S of each energy storage cell C.

[0049] Fig. 4 is a schematic partial side view of the frame member from the outer surface side where the opening of the communication hole in the sealing body is provided. Fig. 5 is a schematic side view showing the relationship between the opening of the communication hole and the frame member. Fig. 5(a) is a side view in a state where the frame member 30 is omitted, and Fig. 5(b) is a side view including the frame member 30. The film 40 is omitted in Figs. 4 and 5.

[0050] 3 to 5, in the energy storage module 1, the openings 31A of a predetermined number (three in this example) of the communication holes 31 that communicate with different energy storage cells C are arranged in overlapping positions when viewed from the first direction D1. The openings 31A of a group (three in this example) of communication holes 31 arranged along the first direction D1 are arranged along the third direction D3. Here, the openings 31A of the communication holes 31 that communicate with the energy storage cells C adjacent in the first direction D1 may be arranged adjacent to each other in the third direction.

[0051] The frame member 30 is configured such that a plurality of portions 30p including a group (three in this case) of frame portions 30f surrounding the respective openings 31A of the group of communication holes 31 are arranged along the third direction D3 when viewed from the second direction D2 intersecting the outer side surface 23s. That is, the frame member 30 includes a plurality of frame portions 30f surrounding the respective openings 31A of the plurality of communication holes 31 when viewed from the second direction D2 intersecting the outer side surface 23s. The space 33 surrounded by the frame portions 30f communicates with the internal space S of the storage cell C via the communication holes 31. However, the length Ts of the space 33 in the first direction D1 is greater than the thickness Tc of the storage cell C in the first direction D1. In this embodiment, the length Ts corresponds to the thickness Tc of the plurality of storage cells C.

[0052] Note that each of the portions 30p including a group of frame portions 30f arranged along the first direction D1 may be integrated with each other. Also, each of the group of frame portions 30f included in one portion 30p may be configured to have a different length Ts in the first direction D1. In this embodiment, the length Ts of the space 33 surrounded by the shortest frame portion 30f in the first direction D1 is made larger by the thickness Tc of the storage cell C.

[0053] As described above, the film 40 is joined to the surface (top surface of the frame portion 30f) opposite to the outer surface 23s of the frame member 30, and seals each of the multiple spaces 33 (i.e., the internal space S and the communication holes 31). That is, the film 40 includes multiple frame sealing portions 41 for sealing the spaces 33 surrounded by each of the multiple frame portions 30f. The film 40 includes the same number of frame sealing portions 41 as the number of frame portions 30f (i.e., the number of openings 31A of the communication holes 31). As described above, the frame member 30 may include multiple frame portions 30f having different lengths in the first direction D1. In this case, the film 40 also includes multiple frame sealing portions 41 having different widths depending on the length of the frame portions 30f in the first direction D1. The film 40 may be made of a single sheet member. That is, the multiple spaces 33 may be sealed collectively by the film 40 made of a single sheet member.

[0054] Before the film 40 is installed, the frame member 30 described above can be used as a liquid injection frame when injecting electrolyte into each internal space S of the electricity storage cell C by pressing a nozzle of an electrolyte injection device against it.

[0055] Next, an example of a method for manufacturing the above-described storage module 1 will be described. FIG. 6 is a flowchart showing main steps of the method for manufacturing the storage module according to this embodiment. FIG. 7 is a schematic side view showing one step shown in FIG. 6. As shown in FIGS. 6 and 7, in this manufacturing method, first, a module to be inspected 1A is prepared (step S10, preparation step). The module to be inspected 1A is similar to the storage module 1 described above.

[0056] In the inspected module 1A (i.e., the energy storage module 1), a film 40 is provided on a frame member 30 in a depressurized chamber to seal the internal space S. Each of the multiple internal spaces S of the inspected module 1A is sealed in a state where the pressure is reduced below atmospheric pressure. Therefore, when the inspected module 1A sealed in a depressurized chamber is placed at atmospheric pressure, each of the frame sealing parts 41 may be recessed so as to protrude inward due to the difference between the pressure in the internal space S and the atmospheric pressure. On the other hand, if a pinhole is formed in any of the frame sealing parts 41, there is a risk that the pressure in the energy storage cell C including the internal space S sealed by that frame sealing part 41 will return to normal during a predetermined characteristic inspection after the depressurized sealing.

[0057] For this reason, in the next step, an airtightness test is performed to detect the pressurized storage cells C (step S20, test step). Fig. 8 is a flowchart showing each step of the airtightness test shown in Fig. 6. Figs. 9 and 10 are schematic diagrams showing one step of the flowchart shown in Fig. 8. As shown in Figs. 8 and 9, in the airtightness test, first, the module 1A to be tested is placed in a vacuum chamber CH (step S201, first step).

[0058] A detector D is disposed outside the vacuum chamber CH for detecting the deformation state of each of the frame sealing portions 41 of the film 40 of the inspected module 1A. The detector D is, for example, a laser displacement meter. In this case, the detector D can detect the deformation state of the frame sealing portion 41 by irradiating laser light L into the vacuum chamber CH through a light-transmitting window portion W provided in the vacuum chamber CH and receiving the reflected light of the laser light L through the window portion W. In step S201, the inspected module 1A is disposed in the vacuum chamber CH such that the film 40 faces the detector D through the window portion W of the vacuum chamber CH.

[0059] In the next step, the vacuum chamber CH is evacuated to reduce the pressure therein (step S202, second step), whereby the pressure in the vacuum chamber CH is gradually reduced from atmospheric pressure.

[0060] 8 and 10, after or during step S202, a detector D is used to detect the deformation state of each of the frame sealing portions 41 of the film 40 (step S203, third step). More specifically, in step S202, the vacuum chamber CH is depressurized until it reaches a predetermined threshold (specified value). Therefore, when there is a storage cell C whose internal pressure is higher than the threshold due to multiple pressures, the frame sealing portion 41 corresponding to the storage cell C deforms from an inwardly convex state to an outwardly convex state (swells to reverse the curvature) at the time when the internal pressure of the vacuum chamber CH becomes lower than the internal pressure of the storage cell C before it reached the threshold.

[0061] In step S203, a detection device D is used to detect the deformation state of the frame sealing portion 41. As an example, when the detection device D is a laser displacement meter, the deformation state (displacement) of the frame sealing portion 41 can be detected as a numerical value or an image by scanning a laser light L over the multiple frame sealing portions 41. Step S203 may be performed during the course of performing step S202, that is, while the vacuum chamber CH is being depressurized, or may be performed after step S202 is completed and the internal pressure of the vacuum chamber CH has reached a predetermined threshold value.

[0062] In the next step, the airtightness of the energy storage cell C is determined (step S204, third step). That is, in step S204, if any frame sealing portion 41 is found to be deformed to a certain degree or more based on the detection result of the deformation state of the frame sealing portion 41 by the detection device D in step S203, it is determined that there is an airtight leak in the energy storage cell C corresponding to that frame sealing portion 41. In this embodiment, when the detection device D detects a frame sealing portion 41 that has been deformed to be convex outward among the frame sealing portions 41, it can be determined that there is an airtight leak in the energy storage cell C corresponding to that frame sealing portion 41.

[0063] As described above, in steps S203 and S204, after or during step S202, an airtightness determination is performed on each of the multiple storage cells C based on the deformation state of each of the multiple frame sealing portions 41 of the film 40. More specifically, before step S202, each of the multiple frame sealing portions 41 of the film 40 is convex toward the inside, and in steps S203 and S204, when or while the pressure is reduced to the threshold value in step S202, if a frame sealing portion 41 that has deformed to be convex toward the outside is detected among the multiple frame sealing portions 41, it is determined that there is an airtight leak in the storage cell C corresponding to that frame sealing portion 41.

[0064] Thereafter, if no leaking energy storage cell C is detected in steps S203 and S204, an exterior film 90 (and conductive members 97, 98) is provided on the inspected module 1A (step S30, exterior step) as shown in Fig. 8. That is, in step S30, the inspected module 1A that has been inspected in step S20 is sealed with an exterior film to form an exterior-equipped module 100 from the inspected module 1A (energy storage module 1).

[0065] As described above, in the energy storage module manufacturing method according to this embodiment, after preparing the inspected module 1A, an inspection step (step S20) is performed to inspect the inspected module 1A for airtightness. The inspected module 1A includes a reduced-pressure internal space S and has a plurality of stacked energy storage cells C. The internal space S communicates, via communication holes 31 in the sealing body 20, with a space 33 surrounded by a frame portion 30f of a frame member 30 provided on the outer surface 23s of the sealing body 20.

[0066] The internal space S is sealed by providing the frame member 30 with a film 40 including a plurality of frame sealing portions 41 for sealing the space 33 surrounded by each of the plurality of frame portions 30f. In the inspection process, the module 1A to be inspected is placed in a vacuum chamber CH (step S201), and then the pressure in the vacuum chamber CH is reduced (step S202). Then, based on the deformation state of each of the plurality of frame sealing portions 40f of the film 40, an airtightness determination is performed for each of the plurality of storage cells C (steps S203, S204). This makes it possible to inspect the airtightness of each storage cell C.

[0067] In particular, the length Ts of the frame portion 30f of the frame member 30 in the stacking direction (first direction D1) of the energy storage cells C is greater than the thickness Tc of the energy storage cells C in the same direction. Therefore, the frame sealing portion 41 that seals the frame portion 30f of the film 40 also has a length Ts greater than the thickness Tc of the energy storage cells C, making it easy to detect deformation. Therefore, even if the energy storage cells C are thin, deformation of the frame sealing portion 41 can be easily detected, making it possible to reliably inspect the airtightness of the energy storage cells C.

[0068] In the energy storage module manufacturing method according to this embodiment, before step S202, each of the multiple frame sealing portions 41 of the film 40 is convex facing inward. Furthermore, in steps S203 and S204, when the pressure inside the vacuum chamber CH is reduced to the threshold value in step S202, or while the pressure is being reduced to the threshold value, if a frame sealing portion 41 that has deformed to be convex facing outward is detected among the multiple frame sealing portions 41, it is determined that there is an airtight leak in the energy storage cell C corresponding to that frame sealing portion 41. This makes it possible to reliably determine whether or not there is an airtight leak in the energy storage cell C.

[0069] In the energy storage module manufacturing method according to the present embodiment, the film 40 is a resin sheet member. In this case, the frame sealing portion 41 is more easily deformed than when it is configured of, for example, a laminate film including a metal layer, so that the deformation of the frame sealing portion 41 can be detected more easily and the airtightness of the energy storage cells C can be inspected more reliably.

[0070] The energy storage module manufacturing method according to this embodiment includes an exterior packaging step (S30) of sealing the inspected module 1A that has been inspected in the inspection step (step S20) with an exterior packaging film 90. This makes it possible to obtain an exterior-packaged module 100 with improved airtightness.

[0071] The above embodiment has been described as an example of the energy storage module manufacturing method according to the present invention. Therefore, the energy storage module manufacturing method according to the present invention is not limited to the above embodiment and can be modified as desired.

[0072] For example, in the energy storage module manufacturing method according to the embodiment, as shown in FIG. 11, each of the frame sealing portions 41 may be formed with a flexible portion 42 that is relatively more flexible than other portions. The flexible portion 42 is, for example, a recess formed by embossing at a position of the film 40 corresponding to each of the frame sealing portions 41. That is, the flexible portion 42 is further recessed so as to be convex inward at the time of step S201. In this case, when the pressure inside the vacuum chamber CH is reduced in step S202, the frame sealing portion 41 is likely to deform so that the flexible portion 42 is convex outward. This makes it possible to more easily detect the deformation of the frame sealing portion 41 and more reliably inspect the airtightness of the energy storage cell C.

[0073] Also, in the above embodiment, an example has been described in which deformation of the frame sealing portion 41 that has been deformed to be outwardly convex is detected in steps S203 and S204 to determine airtightness of the energy storage cell C. However, in steps S203 and S204, it is sufficient to detect the state of deformation of the frame sealing portion 41 to determine airtightness of the energy storage cell C, and the airtightness of the energy storage cell C may also be determined by detecting a state in which the frame sealing portion 41 has been deformed from an inwardly convex state to a flat state or by detecting the amount of depression in the inwardly convex state.

[0074] Furthermore, the film 40 is not limited to being made of resin, and may be made of a material including resin and a material other than resin. Furthermore, in the energy storage module manufacturing method according to the above embodiment, the energy storage module 1 is exemplified as the inspected module 1A, but the inspected module 1A may be a different energy storage module from the energy storage module 1.

[0075] The following additional notes will be given regarding the above embodiment.

[0076] The manufacturing method of the electric storage module according to the appendix includes, [1] "a preparation step of preparing an inspected module having a stack in which a plurality of electric storage cells, each having a reduced-pressure internal space, are stacked along a first direction, a sealing body provided on the stack so as to seal the internal space of the electric storage cell, a frame member provided on an outer surface of the sealing body along the first direction, and a film provided on a surface of the frame member opposite to the outer surface; and an inspection step of performing an airtight inspection of the inspected module after the preparation step, wherein the sealing body has a plurality of communication holes formed therein that communicate with the internal spaces of each of the plurality of electric storage cells and open to the outer surface, and the frame member has a width of about 100 mm when viewed from a second direction intersecting the outer surface. the film includes a plurality of frame portions surrounding each of the openings of the plurality of communication holes, a thickness in the first direction of the space surrounded by the frame portions is greater than a thickness in the first direction of the energy storage cell, the film includes a plurality of frame sealing portions for sealing the spaces surrounded by each of the plurality of frame portions, and the inspection process includes a first process of placing the module to be inspected in a vacuum chamber, a second process of reducing the pressure inside the vacuum chamber after the first process, and a third process of determining the airtightness of each of the plurality of energy storage cells based on the deformation state of each of the plurality of frame sealing portions of the film after the second process or during the second process.

[0077] The storage module manufacturing method in the appendix may be the storage module manufacturing method described in [1] above, [2] "wherein, before the second step, each of the multiple frame sealing portions of the film is convex facing inward, and in the third step, when the pressure inside the vacuum chamber is reduced to a threshold value in the second step or while the pressure is being reduced to the threshold value, if one of the multiple frame sealing portions is detected to have deformed to be convex facing outward, it is determined that there is an airtight leak in the storage cell corresponding to that frame sealing portion."

[0078] The storage module manufacturing method according to the appendix may be [3] "the storage module manufacturing method described in [1] or [2] above, in which each of the plurality of frame sealing portions has a flexible portion that is relatively more flexible than other portions."

[0079] The method for producing an electricity storage module according to the appendix may be [4] "the method for producing an electricity storage module according to any one of the above [1] to [3], in which the film is made of resin."

[0080] The storage module manufacturing method according to the appendix may be [5] "the storage module manufacturing method according to any one of [1] to [4], including an exterior packaging process of sealing the inspected module that has been inspected in the inspection process with an exterior packaging film." [Explanation of symbols]

[0081] 1A...module to be inspected, 10...electrode laminate (laminate), 20...sealing body, 30...frame member, 30f...frame portion, 31...communicating hole, 31A...opening, 33...space, 40...film, 41...frame sealing portion, 42...flexible portion.

Claims

1. a preparation process for preparing an inspected module including: a stack in which a plurality of storage cells, each having a reduced-pressure internal space, are stacked along a first direction; a sealant provided on the stack so as to seal the internal space of the storage cell; a frame member provided on an outer surface of the sealant along the first direction; and a film provided on a surface of the frame member opposite to the outer surface; an inspection step of inspecting the module to be inspected after the preparation step; Equipped with a plurality of communication holes are formed in the sealing body, the communication holes communicating with the internal spaces of the plurality of power storage cells and opening to the outer surface; the frame member includes a plurality of frame portions surrounding respective openings of the plurality of communication holes when viewed from a second direction intersecting the outer surface, a length in the first direction of a space surrounded by the frame portion is greater than a thickness in the first direction of the energy storage cell, the film includes a plurality of frame sealing portions for sealing spaces enclosed by the plurality of frame portions, The inspection step includes: a first step of placing the module to be inspected in a vacuum chamber; a second step of reducing the pressure inside the vacuum chamber after the first step; a third step of determining airtightness of each of the plurality of storage cells based on a deformation state of each of the plurality of frame sealing portions of the film after or during the second step; Including, A method for manufacturing an energy storage module.

2. Before the second step, each of the plurality of frame sealing portions of the film is convex toward an inside, In the third step, when the vacuum chamber is depressurized to a threshold value in the second step or while the vacuum chamber is being depressurized to the threshold value, if any of the frame sealing portions is detected as being deformed to be convex outward, it is determined that there is an airtight leak in the storage cell corresponding to the frame sealing portion. The method for manufacturing an electricity storage module according to claim 1 .

3. Each of the plurality of frame sealing portions has a flexible portion formed therein that is relatively more flexible than other portions. The method for manufacturing an electricity storage module according to claim 1 .

4. The film is made of resin. The method for manufacturing an electricity storage module according to claim 1 .

5. an exterior packaging step of sealing the inspected module, which has been inspected in the inspection step, with an exterior packaging film; The method for manufacturing an electricity storage module according to any one of claims 1 to 4.

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